/* arm_init.c - NEON optimised filter functions

 *

 * Copyright (c) 2014 Glenn Randers-Pehrson

 * Written by Mans Rullgard, 2011.

 * Last changed in libpng 1.6.16 [December 22, 2014]

 *

 * This code is released under the libpng license.

 * For conditions of distribution and use, see the disclaimer

 * and license in png.h

 */

/* Below, after checking __linux__, various non-C90 POSIX 1003.1 functions are

 * called.

 */

#define _POSIX_SOURCE 1

#include "../pngpriv.h"

#ifdef PNG_READ_SUPPORTED

#if PNG_ARM_NEON_OPT > 0

#ifdef PNG_ARM_NEON_CHECK_SUPPORTED /* Do run-time checks */

/* WARNING: it is strongly recommended that you do not build libpng with

 * run-time checks for CPU features if at all possible.  In the case of the ARM

 * NEON instructions there is no processor-specific way of detecting the

 * presence of the required support, therefore run-time detection is extremely

 * OS specific.

 *

 * You may set the macro PNG_ARM_NEON_FILE to the file name of file containing

 * a fragment of C source code which defines the png_have_neon function.  There

 * are a number of implementations in contrib/arm-neon, but the only one that

 * has partial support is contrib/arm-neon/linux.c - a generic Linux

 * implementation which reads /proc/cpufino.

 */

#ifndef PNG_ARM_NEON_FILE

#  ifdef __linux__

#     define PNG_ARM_NEON_FILE "contrib/arm-neon/linux.c"

#  endif

#endif

#ifdef PNG_ARM_NEON_FILE

#include <signal.h> /* for sig_atomic_t */</signal.h>

static int png_have_neon(png_structp png_ptr);

#include PNG_ARM_NEON_FILE

#else  /* PNG_ARM_NEON_FILE */

#  error "PNG_ARM_NEON_FILE undefined: no support for run-time ARM NEON checks"

#endif /* PNG_ARM_NEON_FILE */

#endif /* PNG_ARM_NEON_CHECK_SUPPORTED */

#ifndef PNG_ALIGNED_MEMORY_SUPPORTED

#  error "ALIGNED_MEMORY is required; set: -DPNG_ALIGNED_MEMORY_SUPPORTED"

#endif

void

png_init_filter_functions_neon(png_structp pp, unsigned int bpp)

{

   /* The switch statement is compiled in for ARM_NEON_API, the call to

    * png_have_neon is compiled in for ARM_NEON_CHECK.  If both are defined

    * the check is only performed if the API has not set the NEON option on

    * or off explicitly.  In this case the check controls what happens.

    *

    * If the CHECK is not compiled in and the option is UNSET the behavior prior

    * to 1.6.7 was to use the NEON code - this was a bug caused by having the

    * wrong order of the 'ON' and 'default' cases.  UNSET now defaults to OFF,

    * as documented in png.h

    */

#ifdef PNG_ARM_NEON_API_SUPPORTED

   switch ((pp->options >> PNG_ARM_NEON) & 3)

   {

      case PNG_OPTION_UNSET:

         /* Allow the run-time check to execute if it has been enabled -

          * thus both API and CHECK can be turned on.  If it isn't supported

          * this case will fall through to the 'default' below, which just

          * returns.

          */

#endif /* PNG_ARM_NEON_API_SUPPORTED */

#ifdef PNG_ARM_NEON_CHECK_SUPPORTED

         {

            static volatile sig_atomic_t no_neon = -1; /* not checked */

            if (no_neon < 0)

               no_neon = !png_have_neon(pp);

            if (no_neon)

               return;

         }

#ifdef PNG_ARM_NEON_API_SUPPORTED

         break;

#endif

#endif /* PNG_ARM_NEON_CHECK_SUPPORTED */

#ifdef PNG_ARM_NEON_API_SUPPORTED

      default: /* OFF or INVALID */

         return;

      case PNG_OPTION_ON:

         /* Option turned on */

         break;

   }

#endif

   /* IMPORTANT: any new external functions used here must be declared using

    * PNG_INTERNAL_FUNCTION in ../pngpriv.h.  This is required so that the

    * 'prefix' option to configure works:

    *

    *    ./configure --with-libpng-prefix=foobar_

    *

    * Verify you have got this right by running the above command, doing a build

    * and examining pngprefix.h; it must contain a #define for every external

    * function you add.  (Notice that this happens automatically for the

    * initialization function.)

    */

   pp->read_filter[PNG_FILTER_VALUE_UP-1] = png_read_filter_row_up_neon;

   if (bpp == 3)

   {

      pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub3_neon;

      pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg3_neon;

      pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =

         png_read_filter_row_paeth3_neon;

   }

   else if (bpp == 4)

   {

      pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub4_neon;

      pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg4_neon;

      pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =

          png_read_filter_row_paeth4_neon;

   }

}

#endif /* PNG_ARM_NEON_OPT > 0 */

#endif /* READ */